Solar cells with copper electrodes
Disclosed herein are solar cells comprising semiconductor substrates and Cu electrodes attached thereto, wherein, the Cu electrodes are derived from conductive pastes containing powder mixtures of Cu particles and crystalline Ge particles and glass frits dispersed in organic media.
1. A solar cell comprising a semiconductor substrate and at least one copper (Cu) electrode attached to a front or back side thereof,
wherein the at least one Cu electrode is formed by: (I) applying a Cu-containing conductive paste onto the front or back side of the semiconductor substrate in a predetermined shape and at a predetermined position; (II) drying the Cu-containing conductive paste; and (III) firing the Cu-containing conductive paste to form the at least one Cu electrode,
wherein, the Cu-containing conductive paste comprises:
a) about 10-95 wt % of a powder mixture of Cu particles and crystalline germanium (Ge) particles, and
b) about 0.1-15 wt % of a glass frit, dispersed in
c) an organic medium,
with the total wt % of all components comprising in the paste totaling to 100 wt %, and wherein, (i) the powder mixture comprises about 3-25parts by weight of the crystalline Ge particles, based on 100 parts by weight of the Cu particles; and (ii) the organic medium is comprised of at least one organic polymer dissolved in at least one solvent.
2. The solar cell of claim 1 , wherein, the Cu particles have a particle diameter (D50) of about 1-50 μm.
3. The solar cell of claim 2 , wherein, the Cu particles have a particle diameter (D50) of about 1.5-30 μm.
4. The solar cell of claim 3 , wherein, the Cu particles have a particle diameter (D50) of about 1.5-15 μm.
5. The solar cell of claim 1 , wherein, the crystalline Ge particles have a particle diameter (D50) of about 1-1000 nm.
6. The solar cell of claim 1 , wherein the semiconductor substrate is selected from the group consisting of single-crystal silicons and multicrystalline silicons.
7. The solar cell of claim 1 , wherein, the at least one Cu electrode is formed on the front side of the semiconductor substrate and in the form of a multiple number of parallel conductive fingers and one or more front-side bus bars that are perpendicular to the conductive fingers.
8. The solar cell of claim 1 , wherein, the at least one Cu electrode is formed on the back side of the semiconductor substrate and in the form of one or more back-side bus bars.